The Origins of High Spatial Resolution Secondary Electron Microscopy

1992 ◽  
Vol 295 ◽  
Author(s):  
M. R. Scheinfein ◽  
J. S. Drucker ◽  
J. Liu ◽  
J. K. Weiss ◽  
G. G. Hembree ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Spatial Resolution ◽  
Secondary Electron ◽  
High Spatial Resolution ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Generation Process ◽  
Secondary Electrons ◽  
Electron Generation ◽  
Secondary Electron Generation

AbstractThe secondary electron generation process is studied in an ultra-high vacuum scanning transmission electron microscope using electron coincidence spectroscopy. Production pathways for secondary electrons are determined by analyzing coincidences between secondary electrons and individual excitation events. The ultimate spatial resolution available in scanning electron microscopy is limited by the delocalization of the secondary electron generation process. This delocalization is studied using momentum resolved coincidence electron spectroscopy. The fraction of secondary electrons resulting from localized excitations can explain the high spatial resolution observed in secondary electron microscopy images.

The Energy Spectra of Secondary Electrons

2000 ◽  
Vol 6 (S2) ◽  
pp. 750-751
Author(s):  
David C Joy ◽  
David Braski
Keyword(s):  
Surface Layer ◽  
Electron Microscope ◽  
Secondary Electron ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Energy Spectra ◽  
Yield Coefficient ◽  
Sem Images ◽  
Secondary Electrons ◽  
Scanning Electron

It has been estimated that more than 90% of all scanning electron microscope (SEM) images ever published have been obtained using secondary electrons (SE) which are defined as being those electrons emitted with energies between 0 and 50eV. The properties of these secondary electron are therefore of considerable interest and importance. However, although secondary electrons have been intensively studied since their discovery by Starke in 1901 the majority of the work has been aimed at determining the SE yield coefficient and its variation with energy for elements and compounds. The energy spectrum of secondary electrons has received far less attention although it is evident that the form of the spectrum must have an effect on the image contrast observed in the SEM because SE detectors are energy selective devices. The few studies that have been made have mostly concentrated on spectra obtained from clean samples observed under ultra-high vacuum conditions. This is understandable, because it is certain that the presence of a surface layer of contamination will change the SE spectrum to some degree or other, but it is unfortunate because all specimens in real SEMs are dirty and it is information about this situation that is required.

μm-Scale Lateral Growth of Ga-Monolayers Observed In-Situ by Electron Microscopy

1989 ◽  
Vol 159 ◽  
Author(s):  
J. Osaka ◽  
N. Inoue
Keyword(s):  
Electron Microscopy ◽  
Secondary Electron ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Intensity Difference ◽  
Lateral Growth ◽  
Mbe Growth ◽  
Electron Intensity ◽  
Scanning Electron

ABSTRACTAn ultra high vacuum scanning electron microscope equipped to an MBE system is utilized to study a transient of a surface atomic structure during MBE growth of GaAs and AlGaAs by the alternate supply method. Lateral growth of a Ga-monolayer over microns is realized utilizing Ga droplets. This is confirmed by discriminating the Ga and As top layer by using the secondary electron intensity difference between the Ga and As top layer. The growth mechanism of the Ga monolayer is discussed based on the results.

Scanning Reflection Electron Microscopy of 2x1 Domain Structure of Si(111) Surface

1985 ◽  
Vol 43 ◽  
pp. 264-265
Author(s):  
H.-J. Ou
Keyword(s):  
Electron Microscopy ◽  
Electron Diffraction ◽  
Spatial Resolution ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Intermediate Energies ◽  
Good Spatial Resolution ◽  
Probe Size ◽  
Reflection Electron Microscopy ◽  
Better Than

Studies of the surface structure of silicon with good spatial resolution made recently by reflection electron microscopy, (REM) have complemented and greatly extended the earlier studies, made by LEED and other methods, of the formation of surface reconstruction superstructures such a the Si(111) 7x7. These studies have not included the 2x1 superstructure on (111) surfaces formed by cleaving Si crystals in ultra-high vacuum. We have now investigated the form of the domains of this 2x1 structure by use of a reconstructed REMEDIE system 2.3 (for Reflection Electron Microscopy and Electron Diffraction at Intermediate Energies, 1-20keV). This system has shown a spatial resolution of better than 100Å although resolutions of about 300Å may be more common in practise because of the limitations due to probe size, vibration and signal noise.

Surface Composition of TiO2-Zn Nanotubes by NanoSIMS

MRS Advances ◽  
2016 ◽  
Vol 1 (46) ◽  
pp. 3151-3156
Author(s):  
Indu B Mishra ◽  
Diana Khusnutdinova ◽  
William T Petuskey
Keyword(s):  
Secondary Electron ◽  
High Spatial Resolution ◽  
Surface Composition ◽  
High Vacuum ◽  
Isotopic Analysis ◽  
Ultra High Vacuum ◽  
Actual Content ◽  
Before And After ◽  
Sims Analysis

ABSTRACTTitania nanotubes were prepared by anodic oxidation of Ti. The titania surfaces were partially coated with Zn by reacting zinc acetate with the nanotubes and then annealed. [1] An annealed nanotube cluster was placed carefully on a silicon wafer using tweezers. Secondary electron images were acquired by bombarding with Cs+ and observing the ejected OZn- and OTi- respectively. The SIMS analysis was done in ultra-high vacuum (∼ 10-10 Torr). The location of before and after the SIMS analysis was confirmed by scanning electron microscopy (SEM). Specific areas with various orientations (vertical and horizontal orientations) of the nanotubes were selected for the NanoSIMS 50L analysis. The NanoSIMS 50L is made by Ametek Cameca, Gennevillieres, France and is capable of doing in situ isotopic analysis of surfaces at high spatial resolution (25 nm2). The average ZnO/TiO was ∼1.8%, confirming the actual content of Zn used during synthesis of the nanotubes. Qualitatively, the TiO/ZnO ratio increased with increasing depth implying that ZnO concentration was decreasing as we probed into the nanotubes.

Design of a UHV STEM for Through-The-Lens Electron Spectroscopy

1990 ◽  
Vol 48 (2) ◽  
pp. 380-381
Author(s):  
A. J. Bleeker ◽  
P. Kruit
Keyword(s):  
Secondary Electron ◽  
High Vacuum ◽  
Secondary Electron Emission ◽  
Auger Spectroscopy ◽  
Scanning Transmission Electron Microscope ◽  
Point Of View ◽  
Ultra High Vacuum ◽  
Scanning Transmission ◽  
Auger Spectra ◽  
Coincidence Measurements

Combining of the high spatial resolution of a Scanning Transmission Electron Microscope and the wealth of information from the secondary electrons and Auger spectra opens up new possibilities for materials research. In a prototype instrument at the Delft University of Technology we have shown that it is possible from the optical point of view to combine STEM and Auger spectroscopy [1]. With an Electron Energy Loss Spectrometer attached to the microscope it also became possible to perform coincidence measurements between the secondary electron signal and the EELS signal. We measured Auger spectra of carbon aluminium and Argon gas showing energy resolutions better than 1eV [2]. The coincidence measurements on carbon with a time resolution of 5 ns yielded basic insight in secondary electron emission processes [3]. However, for serious Auger spectroscopy, the specimen needs to be in Ultra High Vacuum. ( 10−10 Torr ). At this moment a new setup is in its last phase of construction.

On the Faceting of Polar Ceramic Surfaces: Microscopy and Holography Studies of MGO(111) Surfaces

1996 ◽  
Vol 54 ◽  
pp. 366-367
Author(s):  
M. Gajdardziska-Josifovska ◽  
B. G. Frost ◽  
E. Völkl ◽  
L. F. Allard
Keyword(s):  
Electron Microscopy ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Electron Holography ◽  
Flat Surfaces ◽  
Transmission Electron ◽  
Excess Surface ◽  
Polar Surfaces ◽  
Salt Structure ◽  
Crystallographic Planes

Polar surfaces are those crystallographic faces of ionically bonded solids which, when bulk terminated, have excess surface charge and a non-zero dipole moment perpendicular to the surface. In the case of crystals with a rock salt structure, {111} faces are the exemplary polar surfaces. It is commonly believed that such polar surfaces facet into neutral crystallographic planes to minimize their surface energy. This assumption is based on the seminal work of Henrich which has shown faceting of the MgO(111) surface into {100} planes giving rise to three sided pyramids that have been observed by scanning electron microscopy. These surfaces had been prepared by mechanical polishing and phosphoric acid etching, followed by Ar+ sputtering and 1400 K annealing in ultra-high vacuum (UHV). More recent reflection electron microscopy studies of MgO(111) surfaces, annealed in the presence of oxygen at higher temperatures, have revealed relatively flat surfaces stabilized by an oxygen rich reconstruction. In this work we employ a combination of optical microscopy, transmission electron microscopy, and electron holography to further study the issue of surface faceting.

Transmission Electron Microscopy of Epitaxial silicides grown by ultra high vacuum deposition

1989 ◽  
Vol 47 ◽  
pp. 462-463
Author(s):  
D. Loretto ◽  
J. M. Gibson ◽  
S. M. Yalisove
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Diffraction ◽  
High Vacuum ◽  
High Energy ◽  
Energy Electron ◽  
Ultra High Vacuum ◽  
Ex Situ ◽  
Transmission Electron

The silicides CoSi2 and NiSi2 are both metallic with the fee flourite structure and lattice constants which are close to silicon (1.2% and 0.6% smaller at room temperature respectively) Consequently epitaxial cobalt and nickel disilicide can be grown on silicon. If these layers are formed by ultra high vacuum (UHV) deposition (also known as molecular beam epitaxy or MBE) their thickness can be controlled to within a few monolayers. Such ultrathin metal/silicon systems have many potential applications: for example electronic devices based on ballistic transport. They also provide a model system to study the properties of heterointerfaces. In this work we will discuss results obtained using in situ and ex situ transmission electron microscopy (TEM).In situ TEM is suited to the study of MBE growth for several reasons. It offers high spatial resolution and the ability to penetrate many monolayers of material. This is in contrast to the techniques which are usually employed for in situ measurements in MBE, for example low energy electron diffraction (LEED) and reflection high energy electron diffraction (RHEED), which are both sensitive to only a few monolayers at the surface.

Studies of Ge/Si(100) and Observation of Atomic Steps on Si(100) using Biassed Secondary Electron Imaging in a UHV STEM

1990 ◽  
Vol 48 (1) ◽  
pp. 308-309
Author(s):  
Mohan Krishnamurthy ◽  
Jeff S. Drucker ◽  
John A. Venablest
Keyword(s):  
Secondary Electron ◽  
Critical Thickness ◽  
Surface Defects ◽  
Film Growth ◽  
Growth Parameters ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Surface Steps ◽  
Epitaxial Crystal Growth ◽  
Electron Imaging

Secondary Electron Imaging (SEI) has become a useful mode of studying surfaces in SEM[1] and STEM[2,3] instruments. Samples have been biassed (b-SEI) to provide increased sensitivity to topographic and thin film deposits in ultra high vacuum (UHV)-SEM[1,4]; but this has not generally been done in previous STEM studies. The recently developed UHV-STEM ( codenamed MIDAS) at ASU has efficient collection of secondary electrons using a 'parallelizer' and full sample preparation system[5]. Here we report in-situ deposition and annealing studies on the Ge/Si(100) epitaxial system, and the observation of surface steps on vicinal Si(100) using b-SEI under UHV conditions in MIDAS.Epitaxial crystal growth has previously been studied using SEM and SAM based experiments [4]. The influence of surface defects such as steps on epitaxial growth requires study with high spatial resolution, which we report for the Ge/Si(100) system. Ge grows on Si(100) in the Stranski-Krastonov growth mode wherein it forms pseudomorphic layers for the first 3-4 ML (critical thickness) and beyond which it clusters into islands[6]. In the present experiment, Ge was deposited onto clean Si(100) substrates misoriented 1° and 5° toward <110>. This was done using a mini MBE Knudsen cell at base pressure ~ 5×10-11 mbar and at typical rates of 0.1ML/min (1ML =0.14nm). Depositions just above the critical thickness were done for substrates kept at room temperature, 375°C and 525°C. The R T deposits were annealed at 375°C and 525°C for various times. Detailed studies were done of the initial stages of clustering into very fine (∼1nm) Ge islands and their subsequent coarsening and facetting with longer anneals. From the particle size distributions as a function of time and temperature, useful film growth parameters have been obtained. Fig. 1 shows a b-SE image of Ge island size distribution for a R T deposit and anneal at 525°C. Fig.2(a) shows the distribution for a deposition at 375°C and Fig.2(b) shows at a higher magnification a large facetted island of Ge. Fig.3 shows a distribution of very fine islands from a 525°C deposition. A strong contrast is obtained from these islands which are at most a few ML thick and mottled structure can be seen in the background between the islands, especially in Fig.2(a) and Fig.3.

scholarly journals Enhanced method for High Spatial Resolution surface imaging and analysis of fungal spores using Scanning Electron Microscopy

2018 ◽  
Vol 8 (1) ◽  
Author(s):  
Gopal Venkatesh Babu ◽  
Palani Perumal ◽  
Sakthivel Muthu ◽  
Sridhar Pichai ◽  
Karthik Sankar Narayan ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Spatial Resolution ◽  
High Spatial Resolution ◽  
Fungal Spores ◽  
Surface Imaging ◽  
Scanning Electron
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